1. Field of the Invention
This invention relates to an angle detecting device and, more particularly, to an angle detecting device suitable for detecting the rotation angle of pedal arms such as an automotive brake pedal or an accelerator pedal.
2. Description of the Related Art
Motor vehicles in these days are equipped with a mechanism capable of constantly detecting the rotation angle of pedal arms such as brake and accelerator pedals, thereby enabling fine control of the braking system and accelerator on the basis of data obtained from the detection. For example, detecting the depth of depression of the brake pedal arm by an angle sensor makes it possible to compute the change with respect to time and accordingly to determine whether or not the driver has made an emergency stop. Therefore, a brake assist mechanism can be adopted in which brake performance during an emergency stop is higher than that during a normal stop.
As an angle detecting device for detecting the rotation angle of the pedal arm as described above, there has been proposed such a technique that unitizes a pedal arm, a shaft for rotatably supporting the pedal arm, an angle sensor which engages with the pedal arm to detect the rotation angle of the pedal arm, and a cabinet supporting each of these members by accurately specifying their relative positions. The angle sensor is provided with a rotating portion (a sensor lever) which is actuated to turn in engagement with the pedal arm, so that, with the rotation of the pedal arm when the pedal is depressed, the rotating portion of the angle sensor will turn in accordance with the depth of depression of the pedal.
The angle detecting device thus assembled as a unit has a high degree of accuracy. However, because existing shaft and pedal arm are unusable, an increased manufacturing cost and accordingly an uneconomical angle detecting device will result.
Therefore, it has been proposed to use an angle detecting device that is comprised of a shaft fixed on a frame which is a part of an equipment body on the motor vehicle, a pedal arm rotatably attached on the shaft, and an angle sensor which is mounted on the frame to detect the rotation angle of the pedal arm. The prior art proposed above will be sufficient if only an angle sensor is employed, using the existing shaft and pedal arm. Therefore, it is very advantageous in the respect of manufacturing cost. Besides, a high detecting accuracy is obtainable if only the relative positional relation of the angle sensor and pedal arm is properly set.
The above-described latter prior art is very advantageous in cost. It, however, is unavoidable for the frame, constituting a part of a large-sized equipment body, to have a dimensional error of a few millimeters. Accordingly it is difficult to install the angle sensor in a desired position on the frame in relation to the shaft and the pedal arm. That is, to insure an accurate detection of the rotation angle of the pedal arm, it becomes imperative to set at a specific value a clearance between the shaft at the center of rotation of the pedal arm and the center of rotation of the rotating portion of the angle sensor, and also to arrange the rotating portion of the angle sensor in a specific position when the rotation angle of the pedal is in an initial zero position. In the prior art, however, position adjustment for setting the angle sensor in a given position in relation to the shaft and the pedal arm is likely to become complicated because of large variations in dimensions of the frame, which serves as the angle sensor mounting surface. Therefore, in case the frame has an excessive dimensional error, it is impossible to obtain a desired detection accuracy notwithstanding the position adjustment of the angle sensor.
It is, therefore, an object of this invention to provide an angle detecting device in which the lever of a pedal arm to be detected is rotatably installed on a shaft which is fixed on a frame; and a bracket for mounting an angle sensor is rotatably installed on the shaft, to thereby enable adjustment of angle sensor position by adjusting bracket position. According to this configuration, a clearance between the angle sensor mounted on the bracket and the shaft can be preset with a high accuracy. In addition, the rotating portion of the angle sensor can be arranged in a desired initial position by adjusting the mounting position of the bracket in relation to the shaft. Consequently, the position of the angle sensor is readily adjustable at the time of mounting, and the rotational angle of the lever to be detected can be detected with high accuracy. In the angle detecting device, therefore, an existing shaft and a detecting lever to be detected are usable, making it unnecessary to unitize the angle detecting device; that is, only installing the angle sensor and the bracket is sufficient, resulting in an advantageous cost.
The angle detecting device of this invention comprises a shaft fixed on a frame, a lever to be detected which is rotatably mounted on the shaft, an angle sensor having a rotating portion which is operated to turn in engagement with the lever to be detected and capable of detecting the rotation angle of the lever to be detected, a bracket mounted with the angle sensor and rotatably attached on the shaft, and an adjusting member capable of changing the mounting position of the bracket in relation to the shaft. The bracket set in a specific mounting position by the adjusting member is fixedly attached to the frame.
In the angle detecting device thus constituted, the bracket mounted with the angle sensor is rotatably attached on the shaft. Therefore there can be specified a clearance with a high accuracy between the angle sensor and the shaft. Furthermore, it is possible to move the center of rotation of the rotating portion of the angle sensor along the direction of rotation while keeping the clearance by adjusting the mounting position of the bracket in relation to the shaft, and to easily adjust the rotating portion of the angle sensor to a desired initial position, and accordingly to accurately detect the rotation angle of the lever to be detected, by means of the angle sensor.
Other objects, together with the foregoing, are attained in the embodiments described in the following description and illustrated in the accompanying drawings.